3 Answers
3

You can use the pmset command to obtain this information. The following command obtains a log of the sleep/wake entries then restricts this to the last entry in the list which should be the most recent sleep:

pmset -g log | grep sleep | tail -n 1

You can obviously play around with anything after pmset -g log to give you what you need.

is what really gives me a clean timeline of sleep/wake events on 10.8.2. powerd does not log anything about it, at least on my system (10.8.2, MacBook Pro Retina 15). The formatting on this site does not do justice to the clean output seen on a shell (that is, given enough width to the window):